The present invention relates to a port closing device for a compressor, and more particularly to a port closing device including a packing that closes a suction port or a discharge port of a compressor and a cap that holds the packing.
After a compressor of a car air-conditioner has been made in a factory, lubricating oil is charged in the compressor. The housing of the compressor has a suction port and a discharge port that are connected with external pipes. After the lubricating oil has been charged in the compressor, the suction port and the discharge port are closed by rubber seal caps that are press-fitted in the ports and serve as port closing devices. Gas tightness test is conducted by using test gas filled in the compressor with the suction and discharge ports closed by the seal caps. After the gas tightness test, the compressor sealed by the seal caps is shipped to a car-assembly plant, where the compressor is mounted on a car with the suction port and the discharge port kept closed by the seal caps.
In a gas tightness test, firstly a gas injection needle is pierced through each seal cap into the compressor for injecting a test gas into the compressor. The compressor thus injected with test gas is then placed in a vacuum vessel for inspection for any gas leakage from the compressor. The seal caps may be considered to have sufficient gas tightness if no gas leakage is recognized. The seal caps may be considered to fail to have sufficient gas tightness if any gas leakage is recognized.
Japanese Unexamined Patent Application Publication No. 11-82858 discloses a passage closing device for a compressor. This passage closing device includes a resin mounting member and a closing member that closes the suction port in the housing of the compressor. The closing member has a cover portion that closes the suction port and a stop portion that stops the closing member from dropping off from the mounting member. The mounting member has at one end thereof a recess through which a stud bolt mounted to the housing may be inserted and at the other end thereof a hole whose diameter is smaller than that of the stop portion of the closing member. The closing member is mounted to the mounting member by press-fitting the closing member into the mounting member in such a way that the stop portion extends out of the hole.
The mounting member thus mounted with the closing member is fixed to the housing. In fixing the mounting member to the housing, the cover portion is press-fitted into the suction port and the mounting member is fixed to the housing by the stud bolt inserted in the recess and tightened by a nut.
Japanese Utility Model Application Publication No. 58-76862 discloses a plug for temporarily closing input/output port as used in a fluid-pressure control device. The plug is made of a synthetic resin having elasticity. The plug includes an annular projecting surface that is in close contact with the surface surrounding the opening of the input/output port and a cylindrical insertion portion that engages with the inner surface of the input/output port. A plurality of axial slits is formed in the insertion portion of the plug. The plug, whose annular projecting surface closes the input/output port, is removable easily because of the slits formed in the insertion portion.
Although the Publication No. 11-82858 disclosing a passage closing device for a compressor mentions nothing about the gas tightness test of the compressor, a needle may be pierced through the closing member made of an elastic member for injecting gas into the compressor. After the needle is pulled out from the closing member, the needle mark left in the closing member is closed by the elastic force of the cover portion that is strengthened by press-fitting the cover portion into the suction port. Thus, the compressor mounted with the passage closing device may be placed in a vacuum vessel for inspection for any gas leakage from the compressor. However, the passage closing device disclosed in the Publication No. 11-82858 is configured so as to seal between an external pipe of the compressor and the inner peripheral surface of the port of the compressor. An O-ring that is commonly used as a sealing member cannot provide sufficient sealing against refrigerant leakage of today's car air-conditioner. A sealing member having a larger seal area than the O-ring is demanded.
The plug disclosed in the Publication No. 58-76862 is designed for sealing between the surface surrounding the port and an external pipe of the compressor. If a gasket is used with the plug, a larger seal area may be provided. In the plug whose projecting surface is not press-fitted into the port, however, needle mark formed by piercing a needle through the plug for gas injection may not be completely closed. Therefore, when the compressor mounted with the plug is placed in a vacuum vessel for inspection for any gas leakage from the compressor, the compressor is highly prone to gas leakage through the needle mark, which makes it impractical to perform the gas tightness test of a compressor.
The present invention is directed to a port closing device for a compressor that seals between a surface of the housing surrounding the port and an external pipe appropriately for performing a gas tightness test of the compressor.